Re: No hash join across partitioned tables?

От: Tom Lane
Тема: Re: No hash join across partitioned tables?
Дата: ,
Msg-id: 489.1276114285@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: No hash join across partitioned tables?  (Robert Haas)
Ответы: Re: No hash join across partitioned tables?  (Bruce Momjian)
Список: pgsql-performance

Скрыть дерево обсуждения

No hash join across partitioned tables?  (Kris Jurka, )
 Re: No hash join across partitioned tables?  (Tom Lane, )
  Re: No hash join across partitioned tables?  (Kris Jurka, )
   Re: No hash join across partitioned tables?  (Kris Jurka, )
    Re: No hash join across partitioned tables?  (Tom Lane, )
     Re: No hash join across partitioned tables?  (Kris Jurka, )
    Re: No hash join across partitioned tables?  (Tom Lane, )
     Re: No hash join across partitioned tables?  (Bruce Momjian, )
      Re: No hash join across partitioned tables?  (Tom Lane, )
       Re: No hash join across partitioned tables?  (Robert Haas, )
        Re: No hash join across partitioned tables?  (Tom Lane, )
         Re: No hash join across partitioned tables?  (Grzegorz Jaśkiewicz, )
         Re: No hash join across partitioned tables?  (Robert Haas, )
          Re: No hash join across partitioned tables?  (Tom Lane, )
           Re: No hash join across partitioned tables?  (Bruce Momjian, )
            Re: No hash join across partitioned tables?  (Tom Lane, )
             Re: No hash join across partitioned tables?  (Bruce Momjian, )
              Re: No hash join across partitioned tables?  (Tom Lane, )
               Re: No hash join across partitioned tables?  (Robert Haas, )
                Re: No hash join across partitioned tables?  (Bruce Momjian, )
          Re: No hash join across partitioned tables?  (Alvaro Herrera, )
           Re: No hash join across partitioned tables?  (Tom Lane, )
            Re: No hash join across partitioned tables?  (Samuel Gendler, )
             Re: No hash join across partitioned tables?  (Alvaro Herrera, )
              Re: No hash join across partitioned tables?  (Samuel Gendler, )
               Re: No hash join across partitioned tables?  (Alvaro Herrera, )
            Re: No hash join across partitioned tables?  (Robert Haas, )
 Re: No hash join across partitioned tables?  (Tom Lane, )
  Re: No hash join across partitioned tables?  (Kris Jurka, )

Robert Haas <> writes:
> In going back through emails I had marked as possibly needing another
> look before 9.0 is released, I came across this issue again.  As I
> understand it, analyze (or analyse) now collects statistics for both
> the parent individually, and for the parent and its children together.
>  However, as I further understand it, autovacuum won't actually fire
> off an analyze unless there's enough activity on the parent table
> considered individually to warrant it.  So if you have an empty parent
> and a bunch of children with data in it, your stats will still stink,
> unless you analyze by hand.

Check.

> Assuming my understanding of the problem is correct, we could:

> (a) fix it,
> (b) document that you should consider periodic manual analyze commands
> in this situation, or
> (c) do nothing.

> Thoughts?

The objections to (a) are that it might result in excessive ANALYZE work
if not done intelligently, and that we haven't got a patch ready anyway.
I would have liked to get to this for 9.0 but I feel it's a bit late
now.

            regards, tom lane


В списке pgsql-performance по дате сообщения:

От: Robert Haas
Дата:
Сообщение: Re: Large (almost 50%!) performance drop after upgrading to 8.4.4?
От: Robert Haas
Дата:
Сообщение: Re: slow query performance